Photocatalytic Degradation of Methylene Blue over TiO2 Pretreated with Varying Concentrations of NaOH

In this paper, different NaOH concentrations (2, 5, 10, and 15 M) were used to treat {001}TiO2. The effect of NaOH on the crystal structure, morphology, optical properties, light raw electronic-hole recombination, and degradation performance of {001}TiO2 on methylene blue were studied. The results demonstrate that rutile TiO2 appeared when the NaOH concentration was as high as 10 M, showing much better photolytic performance than others. As the concentration of sodium hydroxide increases, the morphology changes accordingly. The specific surface area increases and the optical electronic-hole recombination rate decreases. Radical scavenging tests showed that hydroxyl radical and hole are very important in photocatalysis.